Valve, in particular exhaust valve for an internal combustion engine or the like

ABSTRACT

An exhaust valve for an internal-combustion engine with a mushroom head comprising an inner heat-insulating layer of mineral material such as mica extending from a central area to the vicinity of the periphery of said head and interposed between the front end face of the head and the opposite side thereof which is provided with an annular bearing surface portion formed under said head, said heat-insulating layer having a compressive strength sufficient to transmit all the working load integrally to the valve body.

United States Patent Inventor Karl Kuhn Saint-Germain-En-Laye, France Appl. No. 847,900 Filed Aug. 6, 1969 Patented Aug. 17, 1971 Assignee Societe DEtudes De Machines Thermiques Saint Denis (Seine Saint Denis), France Priority Sept. 16, 1968 France VALVE, IN PARTICULAR EXHAUST VALVE FOR AN INTERNAL COMBUSTION ENGINE OR THE LIKE 12 Claims, 2 Drawing Figs.

U.S. Cl ..l23/188 AA, 123/188 A Int. Cl F0ll 3/02, 1 F011 3/20 Field of Search 123/188 AA, 188 A, 188 P References Cited UNITED STATES PATENTS l/l887 Traylor 1,601,274 9/1926 Warrington 1. 123/188 1,868,138 7/1932 Fisk .1 123/158 2,316,488 '4/1943 Rothm. 123/188 2,745,777 5/1956 Clarke..... 123/188 2,882,886 4/1959 Butcher 123/188 FOREIGN PATENTS 11,510 5/1907 Great Britain 123/188 12,662 5/1913 Great Britain 123/188 Primary Examiner-Mark M. Newman Assistant Examiner Ronald B. Cox Attorney-Nolte and Nolte ABSTRACT: An exhaust valve for an internal-combustion engine with a mushroom head comprising an inner heat-insulating layer of mineral material such as mica extending from a central area to the vicinity of the periphery of said head and interposed between the front end face of the head and the 0pposite side thereof which is provided with an annular bearing surface portion formed under said head, said heat-insulating layer having a compressive strength sufficient to transmit all the working load integrally to the valve body.

PATENTED M181 112m SHEET 1 BF 2 w vewrae K424 Aamv- HTTORNE Y3 VALVE, IN PARTICULAR EXHAUST VALVE FOR AN INTERNAL COMBUSTION ENGINE OR THE LIKE The present invention relates to and has essentially for its object a movable member for obturating a passagewayfor a flow of hot fluid and more particularly but not exclusively an exhaust valve for an internal-combustion thermal engine notably of the Diesel-type consuming or burning more especially viscous combustibles or fuels such as heavy petroleum oils, heavy fuel oils or mazut, as well as the various applications and uses resulting from the working thereof.

- It is known that such valves which are generally of the type with a head in the shape of a mushroom or a tulip provided,

' under the head or on the valve-stem side, with an annular bearing surface or portion adapted to come into sealing closing contact with the valve seat, the said annular bearing surface is liable to corrosion, in particular chemical corrosion, notably by the vanadium salts contained in the burnt gases of the said viscous fuels, when their temperature exceeds about 500 C.--.600 C. In order to eliminate this drawback, a known method consists in preventing the annular sealing surface of the valve from reaching this harmful range of temperatures, so as to maintain its temperature below this criticalvalue. To this end, a prior art solution consists in interposing in the interior or in the mass of "the valve head an internal heat-insulating layer between the extreme front face of the valve head, which is directly exposed to the heat of the combustion gases, and the opposite portion of the said valve head, that is the portion carrying the annular sealing surface, so that this heat-insulating layer constitutes an antithermal screen for reducing as much as possible the transmission of heat through conduction to the said annular sealing surface. In certain known valves, this heat-insulating layer is constituted by an annular static-air lamina surrounding the central portion of the valve head and extending "substantially to the vicinity of the periphery of the latter, and this is inconvenient in that it does not provide a sufficiently effective heat insulation and the'hollow thus created within the mass of the valve favors, owing to the resulting weakening of the structure, the appearance of mechanical stresses caused by the external forces, efforts and actions undergone by the valveIAccording to another known solution,

the annular heat-insulating layer has a relatively small radial width and is located only near the periphery of the valve head, so that the thermal barrier thus created exerts only a very insufficient and localized action. This heat-insulating layer is constituted either by a metal-and-plastics gasket filling a recess in the shape of an open peripheral slot or groove or by a rnetallization deposit associated or not with a layer of static air, the annular sealing portion being in this case carried by a built-up ring which is threaded internally and screwed onto a corresponding threaded portion of the valve head so as to define the recess containing the heat-insulating layer. These arrangements are used to protect above all the stationary seat of the valve against excessive heating and are not satisfactory as far as the heat insulation of the annular sealing portion is concerned.

The'purpose of the invention is to eliminate the aforesaid inconveniences by improving the aforesaid known arrangements and the valve according to the invention is remarkable notably in that the said heat-insulating layer is constituted by a solid coherent heat-insulating substance whose mechanical resistance, in particular to compression, is sufficient to transmit substantially integrally all the operating efforts to the valve body. 1

According to another characteristic feature of the invention, the said athermanous substance is a mineral material constituted preferably by mica either in multiple thin sheets superposed or'adjoined into a stack or bundle, or solid, or in flakes agglomerated by a mineral binder eventually vitrifiable through melting.

This arrangement ofiers the advantage of being simple, economical in use and efficient in protecting the annular sealing portion against heat.

According to still another characteristic feature of the invention, the sealing annular portion is integral with a removable annular element substantially coaxial to the valve, in a manner known per se, secured to the valve stem and defining the cavity containing the said heat-insulating layer, so as to exert a clamping pressure upon the said heat-insulating layer. This arrangement offers the advantage of enabling to readily replace or change the said demountable element in case of wear of the annular sealing portion, and this avoids the necessity of replacing the valve as a whole, since the generally integral piece constituted by the main portion of the valve head and by the valve stem may thus be retained' The invention also relates to the devices, apparatus, machines, systems, equipments or plants provided with valves according to the invention and in particular the internal combustion engines of the Diesel-type burning heavy fuel oil.

The invention will be better understood and other characteristics, details and advantages of the latter will appear as the following explanatory description proceeds with reference to the appended diagrammatic drawings given solely by way of example illustrating two forms of embodiment of the invention and wherein:

FIG. 1 is a fragmentary half view of a valve according to the invention, the removable annular element of whichis in one single piece screwed onto the valve stem;

FIG. 2 is a similar view of a modification in which the demountable annular element is in two parts, one of which forms a clamping screw.

According to the form of embodiment of FIG. 1, showing a sectional half view limited by the geometrical axis of revolution, therefore of general symmetry, the valve, notably the exhaust valve of a heavy-fuel (mazut) Diesel engine is made in two pieces one of which is constituted by an integral body I, for instance of special steel, composed of the main portion 2 of the mushroom or tulip valve head and of the valve stem 3, while the other piece 4 placed under the valve head and completing the latter constitutes the demountable annular element carrying, near the peripheral portion of its external surface, the annular sealing portion 5 and screwed by means of its threaded bore 6 onto a corresponding threaded portion 7 of the valve stem, adjacent to the valve head and having preferably a diameter greater than that of the remainder of the valve stem 3. The annular sealing bearing portion 5 is advantageously constituted by a deposit of hard metal alloy, such as stellite, forming a built-up shield.

The mutually confronting faces 8 and 9 respectively of the element 4 and of the main portion of the valve head 2 are conformed so as to define an annular cavity 10, substantially coaxial to the valve head and filled with a substantially incompressible heat-insulating substance 11, advantageously constituted by mica in thin sheets, for instance in the shape of washers or annular disks, superposed into a stack or bundle held clamped between the element 4 and the head 2. The space 10 occupied by the heat-insulating layer 11 may have substantially the shape of a conical ring as shown in the drawing or possibly of a cylindrical ring or the like and this space communicates advantageously permanently radially with the exterior through the medium of a continuous circular peripheral slit 12 provided on a lateral surface or wall of the valve head and forming a separating interval between the element 4 and the head 2 for preventing any direct transmission of heat through conduction from the valve head 2, exposed to high-temperature burnt gases, towards the annular sealing shield 5. The peripheral lateral surface 13 of the demountable element 4, which is for instance at least approximately parallel to the axis of revolution of the valve, has preferably a width or height parallel to this axis, of a minimum value in order to reduce as much as possible the area liable to be in contact with the hot gases.

The cavity 10 containing the heat-insulating material 11 is advantageously defined by two walls for instance substantially cylindrical, coaxial, spaced 14, 15, respectively radially external and internal, each extending from a lateral wall 9, 8 of the remaining spaced from the latter, so as to provide a free interval forming a slit with for instance substantially parallel walls. 1

The two extreme walls 14 and 15 are .connected for instance respectively to the opposite lateral walls 9, 8, so that the wall 14 is constituted by a peripheral flange of the valve head 2, whose respectively terminal extreme and lateral internal faces penetrate at least partially with clearances into a corresponding cooperating recess defined by a shouldered groove or rabbet 16 provided on the internal face of the element 4, in order to prevent the egress of the heat-insulating material 11 and thus constituting the slit 12. The wall 15 is constituted by an annular, radially internal flange of the element 4, so that the extreme terminal face remains spaced from the face 9 of the valve head so as to constitute an annular passage slit 17 preventingany thermal bridge at that location and advantageously interconnecting the cavity 10 and an annular recess 18 defined respectively by a wall portion of the element 4 and a depression or countersink adjacent to the threaded portion 7. The cavity 18 is filled with static air and contributes togetherwith the screw-joint portion 6, 7 to the heat insulation of the impervious bearing shield 5, the major part of the heat absorbed by the valve head 2 thus being eliminated or dissipatedby conduction through the main mass of the said head and by the valve stem, so that the impervious bearing liner remains at a temperature below 500 C.--600 C.

The annular element 4 comprises, at the level of its threaded portion, gripping or seizing means, such as flats or sides,'or for instance two substantially radial and diametrically opposed holes 19 allowing the insertion of a tool such as a pin or key for driving it in rotation. The screwed joint between the annular element 4 and the valve stem is preferably braked or blocked by any appropriate means (not shown such as caulking or hammering, weld spot, cone-pointed screw, or the like). Thescrewed joint may be replaced by forced fitting or by a brazed or welded joint. The radial dimension and the location of the cavity must be such as to allow the heat-insulating layer 11' to extend from the vicinity of the periphery of the valve head 2, substantially at the level of the sealing shield 5 to the central or axial zone of the valve head.

In the alternative embodiment shown in FIG. 2 where the same reference numerals as in FIG.. 1 have been used to denote identical or similar parts, the removable annular element 4a is constituted by two pieces, one 20 of which carries the sealing liner 5 and forms a clamping plate for the heat-insulating layer 11, while the other piece 21 is constituted by an internally threaded sleeve, socket or ring forming a clamping not for the plate 20 and screwed onto the cooperating threaded portion 7 of the valve stem. This solution is advantageous in that in order to replace the annular sealing portion 5 in case of wear of the latter, it is sufficient to change the plate 20 which affords simple and economical manufacture, while keeping the nut-forming threaded portion 21, thus reducing the cost of the replaced piece. 7

The piece '20 is advantageously centered by fitting by its bore 22 onto an appropriate centering portion 23 of the valve head adjacent to the thread countersink 18. The clamping nut 21 is advantageously shouldered at 24 on its face contacting the piece 20. Means are eventually provided to prevent any rotation of the plate 20 and are constituted for instance by at least one pin or the like 25 penetrating into corresponding holes opposite the portions 20 and 2. Another means for preventing the piece 20 from rotating consists in providing at least one flat on the cooperating surfaces of respectively the bore 22 and the fitting surface 23.

The radially internal extreme wall 15 defining the cavity 10 forms in this ,case part of the main portion of the valve head 2 in which is for instance entirely provided the cavity 10 and is connected to a radial face substantially parallel to the face opposite the piece 20 from which it is spaced so as to constitute the annular slit 17.

Of course, the invention is by no means limited to the forms of embodiments described and illustrated which have been given only by way of example. in particular, it comprises all the means constituting technical equivalents to the means described as well as their combinations, should the latter be carried outaccording to the spirit of the invention.

What I claim is: l. A mushroom-type exhaust valve for internal-combustion engine, having a body with a stem and with a mushroom head;;

said head comprising: a front end face; an annular working bearing surface portion formed under said head i.e. on the stem side thereof; an annular cavity formed in coaxial relation to and within said head and extending from a central zone to the vicinity of the periphery of said head between said front end face and the opposite side provided with said bearing surface portion, said cavity communicating radially with the outside through a continuous circular peripheral open slit provided on the lateral peripheral surface of said head between said front end face and said bearing surface portion; and an annular heat-insulating layer of mica substantially filling said cavity and leaving free said slit.

2. A device according to claim 1, wherein said mica is provided in multiple superposed thin sheets forming a stack.

3. A device according to claim 1, wherein said heat-insulating layer is plain mica. i v

4. A device according to claim 1, wherein said mica is formed of flakes agglomerated by a mineral binder vitrifiable through melting.

5. A device according to claim 1, wherein the space occupied by the said heat-insulating layer is defined by two substantially cylindrical, respectively radially inner and outer, coaxial, spaced walls, extending each one from one sidewall of the said cavity to the vicinity of the opposite sidewall thereof while remaining spaced from the latter, so as to provide a free gap.

6. A device according to claim 5, wherein said gap forms on the one hand said slit located radially outwards and on the other hand a radially inner annular slot.

7. A device according to claim 6, wherein said annular element defines a hollow annular coaxial enclosed space filled with static air between said cavity and the connection of said annular element with said stem, said hollow space communicating with said cavity through said slot.

8. A device according to claim 1, wherein said annular bearing surface portion is integral with a removable annular element substantially coaxial with the valve, secured to the valve stem and defining said cavity, so as to exert a clamping pressure on said heat-insulating layer.

9. A device according to claim 8, wherein said annular element is secured to said valve stem by locked screw-threaded means engaging corresponding screw-threaded portions of said valve stem.

10. A device according to claim 8, wherein said annular element is secured to said valve stem by a tightfit.

11. A device according to claim 8, wherein said annular element issecured to said valve stem by a weld.

12. A device according to claim 8, wherein said annular element is composed of two parts, one of which comprises said bearing surface portion and is fitted onto a centering surface of the valve head, while the other part forms a shouldered clamping nut, screwed onto the valve stem, means being provided to prevent the rotation of said one part. 

1. A mushroom-type exhaust valve for internal-combustion engine, having a body with a stem and with a mushroom head; said head comprising: a front end face; an annular working bearing surface portion formed under said head i.e. on the stem-side thereof; an annular cavity formed in coaxial relation to and within said head and extending from a central zone to the vicinity of the periphery of said head between said front end face and the opposite side provided with said bearing surface portion, said cavity communicating radially with the outside through a continuous circular peripheral open slit provided on the lateral peripheral surface of said head between said front end face and said bearing surface portion; and an annular heat-insulating layer of mica substantially filling said cavity and leaving free said slit.
 2. A device according to claim 1, wherein said mica is provided in multiple superposed thin sheets forming a stack.
 3. A device according to claim 1, wherein said heat-insulating layer is plain mica.
 4. A device according to claim 1, wherein said mica is formed of flakes agglomerated by a mineral binder vitrifiable through melting.
 5. A device according to claim 1, wherein the space occupied by the said heat-insulating layer is defined by two substantially cylindrical, respectively radially inner and outer, coaxial, spaced walls, extending each one from one sidewall of the said cavity to the vicinity of the opposite sidewall thereof while remaining spaced from the latter, so as to provide a free gap.
 6. A device according to claim 5, wherein said gap forms on the one hand said slit located radially outwards and on the other hand a radially inNer annular slot.
 7. A device according to claim 6, wherein said annular element defines a hollow annular coaxial enclosed space filled with static air between said cavity and the connection of said annular element with said stem, said hollow space communicating with said cavity through said slot.
 8. A device according to claim 1, wherein said annular bearing surface portion is integral with a removable annular element substantially coaxial with the valve, secured to the valve stem and defining said cavity, so as to exert a clamping pressure on said heat-insulating layer.
 9. A device according to claim 8, wherein said annular element is secured to said valve stem by locked screw-threaded means engaging corresponding screw-threaded portions of said valve stem.
 10. A device according to claim 8, wherein said annular element is secured to said valve stem by a tightfit.
 11. A device according to claim 8, wherein said annular element is secured to said valve stem by a weld.
 12. A device according to claim 8, wherein said annular element is composed of two parts, one of which comprises said bearing surface portion and is fitted onto a centering surface of the valve head, while the other part forms a shouldered clamping nut, screwed onto the valve stem, means being provided to prevent the rotation of said one part. 